Wireless underground sensors are quietly rewriting the rulebook for farm data

Over the last decade, farmers have been promised a torrent of data from the “Internet of Things.” Some of it has delivered—satellite imagery, on-equipment telemetry, and weather stations now inform many day‑to‑day decisions. Yet the most valuable signals in agriculture often live where radios don’t: below the soil surface. That’s where wireless underground sensor networks are stepping in, offering direct, root‑zone visibility without the compromises of aboveground hardware.

These systems bury small, battery-powered nodes that measure moisture, temperature, electrical conductivity, and sometimes nutrients at depths that match crop root zones. The nodes relay data through the soil to a nearby aboveground gateway or to each other in short hops, creating a map of conditions that’s grounded—literally—in what plants actually experience. For irrigated operations, it’s the difference between scheduling water because the forecast says so, and scheduling water because the plant-soil system needs it.

Why go underground?

Aboveground sensors have improved, but they carry tradeoffs that farmers know well: posts and solar panels get in the way of fieldwork, are vulnerable to theft and weather, and sample only the top few centimeters of soil unless paired with cables and drilled probes. By contrast, wireless underground sensors are tucked out of sight, rarely disturbed by equipment, and placed exactly where data matters—the active root zone of a given crop and soil type.

• Fewer fieldwork conflicts: Nodes sit below tillage or at known depths, letting planters, sprayers, and harvesters pass overhead without detours.
• Higher signal relevance: Readings reflect water availability at depth rather than just surface wetness, improving irrigation timing and variable-rate decisions.
• Lower visual and wildlife impact: No posts or panels to attract curiosity or require mowing.

The hard part: radio inside dirt

Soil is a tough medium for wireless signals. Moisture, clay content, and salinity all increase attenuation, which shortens range and drains batteries if systems aren’t designed carefully. Two families of approaches have emerged:

• Sub‑GHz radio with clever waveforms: Protocols like chirp spread spectrum (often associated with LoRa) and other narrowband techniques can push a signal a few meters through typical soils to an aboveground gateway or vertical antenna. Performance varies—sandy, dry soils are friendlier than wet clays—but even short underground hops can be enough if nodes are placed strategically.
• Magnetic induction (MI) links: Instead of radiating traditional radio waves, MI uses low‑frequency magnetic fields produced by coils. Magnetic fields are less affected by water content, allowing more predictable links in damp soils, albeit over shorter distances. MI nodes often forward data among nearby neighbors until it reaches a surface receiver.

Most commercial systems combine these with robust error correction and duty‑cycling to minimize energy use. The upshot for growers is straightforward: don’t expect acres‑wide connectivity from a single buried node, but do expect stable, short-range underground links that are good enough to move small packets of sensor data out of the soil reliably.

Power without panels

Power is the other engineering challenge. Underground nodes can’t rely on solar panels. Today’s deployments typically use long‑life primary batteries paired with firmware that wakes sensors briefly for measurement and transmission, then returns to deep sleep. Under conservative duty cycles (for example, reading every 15–30 minutes and transmitting every hour), field life of 5–10 years is achievable in many cases, influenced by temperature, soil chemistry, and radio conditions.

Research labs and a handful of pilots are exploring energy harvesting to extend or replace batteries:

• Microbial fuel cells that tap soil biochemistry for trickle power.
• Inductive top‑ups from a coil on a passing vehicle or robot, enabling maintenance “drive‑bys.”
• Thermal harvesting that captures small temperature gradients between day and night or soil layers.

For now, battery-first designs dominate because they’re simple, predictable, and easier to deploy at scale.

What growers use them for today

The technology’s initial traction has come in situations where root‑zone precision directly drives profit or risk reduction:

• Drip and micro‑irrigated specialty crops: Almonds, grapes, berries, and orchard crops benefit from precise soil moisture bands. Sensors at multiple depths verify that irrigation events reach—and don’t overshoot—the target zone, reducing leaching and pumping costs.
• Row crops on variable soils: In potatoes, sugar beets, and corn, short-radius underground networks reveal how lightweight soils dry down compared with heavier patches, informing zone-specific irrigation or fertigation.
• Greenhouse and substrate monitoring: Buried or embedded nodes in raised beds and substrates watch root‑zone EC and moisture to tweak feed recipes and irrigation intervals.
• Sports turf and municipal landscapes: While not row‑crop agriculture, the same sensors are seeing use in stadiums and city medians to conserve water without sacrificing turf health—an indicator that the hardware can survive real‑world installation and maintenance cycles.

From raw readings to decisions

Hardware only matters if it changes how water, nutrients, or labor are scheduled. That hinges on data services, not just sensors. Modern platforms aggregate time series from each node and layer on analytics such as:

• Depth‑specific depletion curves that show how fast plants draw water after an irrigation or rainfall event.
• Root activity indicators (e.g., where drawdown is happening) to guide emitter placement, pulse timing, and set lengths.
• Leaching risk alerts when wet fronts move beyond the active root zone in sandier spots.
• Irrigation verification that compares intended application with observed infiltration to catch clogged lines or pressure issues quickly.

Integration with pump controllers and valve manifolds is increasingly common, enabling closed‑loop irrigation where growers set guardrails and the system executes within them.

Economics: where the ROI comes from

Costs vary by vendor and feature set, but as a rule of thumb in 2025:

• Buried nodes: roughly $60–$200 per sensor position, often discounted in bundles.
• Gateways: $300–$1,000 depending on cellular or farm Wi‑Fi backhaul.
• Software/service: $2–$10 per node per month for data storage, alerts, and dashboards.

Returns show up in three line items:

• Water and energy savings: Cutting 10–25% of irrigation in blocks that were historically overwatered can pay for sensor networks in one to three seasons, especially where water or electricity is expensive.
• Yield and quality stability: Avoiding stress peaks improves uniformity, reduces defects in sensitive crops, and can lift overall packout.
• Labor efficiency: Fewer field checks, faster troubleshooting, and confidence to irrigate at night or off‑peak can add meaningful savings.

As always, results depend on how often decisions are adjusted because of the data. The biggest wins tend to come from fields with known variability or chronic over‑ or under‑irrigation issues.

Installation and durability

The sweet spot for burial depth is usually 10–30 cm for shallow-rooted crops and 30–60 cm for orchards and vineyards, with some systems stacking multiple sensors vertically. Successful deployments share a few practices:

• Map and mark placements in farm GIS to avoid future tillage or ripping conflicts and to support quick replacement if needed.
• Align with management zones so each node represents a consistent patch of soil and irrigation conditions.
• Check links before backfilling to confirm connectivity to the gateway; small positioning changes can make a big difference underground.

Housings are typically sealed to IP68 or better, with potting compounds and corrosion‑resistant materials. Even so, extreme salinity, freeze‑thaw cycles, and rodent activity are real‑world stressors. Planning for a small annual replacement rate in budgets is prudent.

Connectivity and standards

Buried nodes generally do not speak directly to public cellular networks or satellites. Instead, they connect to a farm‑level gateway via MI or sub‑GHz radio, and the gateway backhauls data over cellular, satellite, or farm internet. On the spectrum front, most systems operate in license‑exempt ISM bands (for example, 433 MHz or 868/915 MHz), under existing Part 15/ETSI rules for low‑power devices. Magnetic induction approaches, because of their near‑field nature, also fall under unlicensed frameworks but with different compliance tests.

Interoperability is still evolving. Some vendors leverage LoRaWAN above ground while using proprietary underground links. Others keep the entire stack proprietary to optimize for power and range. For growers, the practical questions are: Can the gateway serve multiple blocks? How hard is it to add more nodes later? And can data be exported to existing farm platforms?

Limitations and failure modes to understand

• Wet clays are harsh on radio: After heavy rain or irrigation, underground range can shrink. Good designs account for this with adaptive data rates or by placing nodes closer together.
• Battery life is finite: A realistic service plan includes periodic health checks and an approach to end‑of‑life retrieval or replacement.
• Single‑point sampling risk: One sensor represents a tiny volume of soil. Networks mitigate this with multiple nodes per management zone; a lone probe is best for trend watching, not absolute decisions.
• Data overload without context: Root‑zone moisture curves are powerful but need crop‑stage context and irrigation system constraints to translate into actions.

Environmental considerations

As deployments scale, end‑of‑life handling matters. Some manufacturers now design enclosures for easier retrieval and offer take‑back programs. Others are experimenting with biodegradable components where regulations and performance allow. Growers can ask for material disclosures, recycling options, and expected retrieval rates to minimize e‑waste accumulation in fields.

What’s next

The innovation pipeline is active. Three developments to watch over the next 12–24 months:

• Drone “drive‑by” data mules: Small UAVs or UGVs that overfly or traverse a field to wake low‑power nodes and collect buffered data, reducing the need for fixed gateways in remote blocks.
• Inline nutrient sensing: Early versions can estimate nitrate or ammonium via ion‑selective electrodes. If stability improves, fertigation could be tuned with the same precision that moisture sensing brought to irrigation.
• Smarter edge analytics: On‑node models that learn local soil behavior and compress data, transmitting only significant changes to extend battery life.

Practical checklist for buyers

• What burial depth and sensor types are available, and do they match my crop and soil?
• How does the system maintain connectivity in wet conditions and heavy clays?
• What is the documented battery life at my intended sampling rate and temperature range?
• Can the gateway cover multiple fields, and what backhaul options are supported?
• How are nodes mapped and retrieved, and what end‑of‑life program is offered?
• Can I export raw and processed data to my agronomy software?
• What service level is included—installation, calibration, seasonal checks, agronomic support?

The bottom line

Wireless underground sensor networks won’t replace agronomists or weather forecasts, and they won’t magically make poor irrigation infrastructure perform like new. What they do is remove a persistent blind spot by measuring where plants live and decisions matter. For operations that irrigate, fertigate, or manage high‑value crops with tight margins for error, that visibility can be the difference between guessing and knowing—quietly, out of sight, and as often as you need it.